The correct answer is (c) 0.861
For explanation: Given,
Porosity of 30%=0.3
voids ratio in the loosest state emin= 0.35
voids ratio in the densest state emax=0.92
e=\(\frac{n}{(1-n)}\)
e=\(\frac{0.3}{(1-0.3)}\)
e=0.429
ID=\(\frac{(e_{max} – e)}{(e_{max}-e_{min})}\)
ID=\(\frac{(0.92 –0.429)}{(0.92-0.35)}\)
ID= 0.861.